1. Field of the Invention
The present invention relates to wiretapping and, more particularly, to a method and system for wiretapping packet based communications, so as to facilitate compliance with governmental mandates for instance.
2. Description of Related Art
Techniques currently exist for wiretapping voice calls. In a traditional circuit-switched telephone network, for example, a wiretap can be readily implemented by identifying a specific telephone line or channel (e.g., TDM time slot, for instance), intercepting the electrical signal carried along that line, and communicating those signals to a surveillance equipment operator. In response to a proper court order, a telecommunications service provider may thereby provide law enforcement officials with real-time access to voice calls.
With the growth of the Internet and other such technology, voice traffic is now often carried from point to point over a packet-switched communication path rather than over a circuit-switched communication path. In this arrangement, a voice signal may be digitized and encoded and the resulting bit stream then divided into a sequence of payload blocks. A header is added to each payload block, thereby establishing a packet. Each packet is then routed independently to a destination address in the packet header. And at the destination address, the packets are then assembled, and the payload is extracted, decoded and converted back into the underlying voice signal.
On Oct. 25, 1994, the United States government enacted the Communications Assistance for Law Enforcement Act (CALEA) to make clear a telecommunications carrier's duty to cooperate in the interception of communications for law enforcement purposes. CALEA requires telecommunications service providers (e.g., telephone companies, etc.) to make available both call content (voice signals) and call data (digits dialed, length of call, etc.) to requesting law enforcement agencies in response to a valid court order. Based on the statute, service providers may soon have to facilitate wiretapping of packet-based voice traffic.